FR2985324A1 - SECURITY DEVICE - Google Patents

Abstract

Security device comprising at least a first pattern (A) visible through a lenticular array (2) according to a first axis of vision (Deltaalpha) associated and at least one second pattern (B) visible through said lenticular network (2 ) according to a second axis of vision (Deltabeta) associated, each second axis of vision (Deltabeta) being oriented relative to at least a first axis of vision (Deltaalpha) according to a "pitch angle" characteristic of the lenticular network (2), wherein said at least one second pattern (B) is a function of at least one angle (alpha) of a first axis of vision (Deltaalpha) relative to a normal (DeltaN) to the device (1). Method of manufacturing such a safety device Application to an identity document.

Description

The present invention relates to a security device based on a multiple pattern display through a lenticular array. Such a security device is typically intended to be affixed to a medium, such as an identity document, in order to authenticate it. To this end, a security device is difficult to reproduce in order to make it difficult to manufacture or reproduce such a device. Moreover, such a security device is advantageously customizable so as to make it unique. A lenticular network, also called lenticular sheet, is composed of elementary lenses of the same optical characteristics, the lenticules, which have the particularity of having a focal length such that the rear face, the smooth face, of the lenticular network is confused with the focal plane of the lenticules. Each lenticule enlarges, in an image under the lenticular array, an elemental area that is located in alignment with the eye and the optical center of the lenticule. In order to achieve such a multiple patterned image, at least two embodiments are known. A first embodiment, which is called "preprinted" allows, by arranging a specially adapted image under a lenticular array, to display 30 different patterns, each pattern being visible individually along a proper viewing axis. It is thus possible to produce a composite image, adapted to the lenticular network under which it is arranged, comprising n patterns. Each such pattern is visible along an axis of view proper to the pattern. One passes from one axis of vision to another neighboring axis of vision by a rotation according to a "pitch angle" characteristic of the lenticular network.

Such an adapted image is typically made separately taking into account said "angular step" to be then assembled with the lenticular array. According to a second embodiment, which is called "post-engraved", it is still possible to make a pattern, by etching in a layer. Said layer is predisposed under a lenticular array and is changeable remotely through the lenticular array. Etching is typically performed by means of a beam, such as a laser beam, through said lenticular array. Said beam modifies said layer by adding energy. Said beam is oriented, relative to the device, along a main axis which determines an axis of vision according to which said pattern thus etched is then visible. It is also possible by changing the relative orientation between the device and the engraving tool, between two successive engravings, to make multiple patterns. If such a change in relative orientation between two engravings respects the "angular pitch" of the lenticular array, the etched patterns will be distinct and separately visible each along a proper axis of vision, without interference between the patterns. Due to the principle of modification, the etching only makes it possible to produce monochrome patterns. The two preceding embodiments "pre-printed" and "post-etched" make it possible to produce rather similar devices, in that they comprise n separate patterns, each visible along a line of vision proper to the pattern. One axis of vision is passed from one pattern to another by a rotation of the device respecting the "angular step" or at an angle multiple of the "angular pitch" characteristic of the lenticular network. Each embodiment employed alone offers, by virtue of its intrinsic complexity of implementation, relative protection against unauthorized reproduction. However, it is desired more effective protection for such a safety device.

It seems a priori impossible to combine the two previous embodiments. Indeed, it is appropriate to respect the constraint of "angular step" between two patterns, at the risk otherwise of making patterns superimposed. In the first embodiment "pre-printed", the "angular step" is intrinsically respected during the manufacture of the image, which incorporates this "angular step". In the second "post-engraved" embodiment, the "angular step" is respected by a relative change of orientation of the engraving axis, between two engravings of successive patterns, according to a rotation respecting the "angular step" . The respect of the "angular pitch" is here made relative to the axis of vision / etching of the first pattern. However, according to the first embodiment "pre-printed", during assembly of the image under the lenticular array, there is obtained an axis of vision corresponding to a first pattern having a random orientation angle. The orientation angle of this axis of vision is unknown, it seems impossible to engrave a second pattern, according to the second embodiment "post-engraved", which would be removed from an angle respecting the "angular step". The present invention, however, proposes a safety device and a manufacturing method ingeniously and non-obviously combining the two previously described embodiments "pre-printed" and "post-engraved". This combination, by incorporating into the embodiment by etching of a second pattern, the inherent characteristics resulting from the production of a first printed pattern is also highly synergistic. The invention relates to a safety device comprising at least a first visible pattern through a lenticular network according to a first associated axis of vision and at least a second pattern visible through said lenticular network according to a second axis of vision associated, each second axis of vision being oriented relative to at least a first axis of vision according to a "pitch angle" characteristic of the lenticular array, said at least one second pattern being a function of at least one angle of a first axis of vision relative to a normal device. According to another characteristic of the invention, the second pattern is a function of at least one position of a first pattern relative to the device.

According to another characteristic of the invention, the second pattern is deformed by applying a function transformation of at least one angle of a first axis of vision. According to another characteristic of the invention, said transformation is such that it corrects on said at least one second pattern the effect produced by a rotation orienting the second axis of vision according to the normal, so that said at least one second motive does not appear deformed when viewed according to the second axis of vision. According to another characteristic of the invention, the device is plane and said transformation is an application of a multiplying coefficient to the dimension of the second pattern perpendicular to an axis of a rotation orienting the second axis of vision according to the normal, said Ratio being equal to the sine of the angle of the second axis of vision relative to the normal. According to another characteristic of the invention, a second pattern, as seen along a second associated axis of vision, is complementary to a first pattern, as seen along a first associated axis of vision. According to another characteristic of the invention, the lenticular network is cylindrical along an axis of extension. The invention further relates to an identity document comprising such a security device. The invention also relates to a method of manufacturing a security device comprising the following steps: printing of at least a first pattern capable of being seen through a lenticular network, assembly of said printed pattern under said lenticular network, determination a first axis of vision according to which a first pattern is visible, rotation of the device according to a "pitch angle" characteristic of the lenticular array so as to present the device along a second axis of vision, making a second pattern along the second axis vision through the lenticular network.

According to another characteristic of the invention, the method also comprises, prior to the embodiment step, a step of constructing the second pattern so that its content is a function of an angle of the first axis of vision relative to a normal to the device. .

According to another characteristic of the invention, the method also comprises, prior to the production step, a step of constructing the second pattern so that its content is a function of the position of a first pattern relative to the device.

According to another characteristic of the invention, the construction step is such that the second pattern has a complementarity with the first pattern. According to another characteristic of the invention, the assembly step comprises adding a layer of modifiable material, and the step of producing the second pattern comprises etching in said layer of modifiable material by means of a beam , through the lenticular network.

Other features, details and advantages of the invention will become more apparent from the detailed description given hereinafter in connection with drawings in which: FIG. 1 shows a block diagram of a multiple pattern device based on a lenticular network, - Figure 2 shows a diagram of a method according to the invention, - Figure 3 illustrates an example of transformation T, - Figures 4-6 show different examples of complementarity between patterns.

As illustrated in FIG. 1, a lenticular network 2 comprises a periodic succession of lenticules 3, each having a substantially semicircular profile. It is possible to make lenticular networks 2 of different types. A first type is a cylindrical lenticular network 2. In a cylindrical lenticular network 2, each lenticule 3 has a substantially semicylindrical profile. The cylindrical lenticules 3 are parallel to each other. Each lenticule 3 enlarges an elementary zone in the form of a band of width corresponding to the width of a lenticule 3, of an image located under the lenticular network 2. Another type of lenticular network is obtained by crossing in the same plane of two such cylindrical lenticular networks. In such a network the lenticules 3 are substantially cubic with four rounded upper edges. Such a lenticule 3 has a square shape in the plane of the lenticular network 2 and a semicircular shape in the two perpendicular planes 25 passing respectively through the two axes of the cylinders. The lenticules 3 are organized according to a square matrix. Each lenticule 3 enlarges an elementary zone or pixel in the form of a square with two sides / square cross with two branches whose two widths of the sides / branches correspond to the width of a lenticule 3, of an image situated under the lenticular network. 2. In generalizing, another type of lenticular network 2 is obtained by crossing in the same plane n such cylindrical lenticular 2 networks. In such a network the lenticules 3 are substantially polygonal on 2n sides with 2n rounded upper edges. Such a lenticule 3 has a polygonal shape with 2n sides in the plane of the lenticular network 2 and a semicircular shape in the n perpendicular planes passing respectively by the n axes of the cylinders. The lenticules 3 are organized according to a matrix. Each lenticule 3 enlarges an elementary zone or pixel in the form of a polygon with 2n sides / cross with 2n branches whose widths of the 2n sides / branches correspond to the width of a lenticule 3, of an image situated under the lenticular network 2. By considering an infinite number n, a spherical lenticular network 2 is obtained. In such a spherical lattice the lenticules 3 are substantially hemispherical. Such a lenticule 3 has a circular shape in the plane of the lenticular network 2 and a semicircular shape in any plane perpendicular to the plane 15 of the lenticular network 2. The lenticules 3 are typically organized in a square matrix (checkerboard) or hexagonal (in nest bee). Each lenticule 3 magnifies an elementary zone or circle-shaped pixel of diameter corresponding to the width / diameter of a lenticule 3, of an image located under the lenticular network 2. The invention is applicable to any type of network. 2. Figure 1, one-dimensional, is thus applicable to all types of lenticular array 2. It shows a section along a plane normal to the surface of the lenticular network 2. In the case of a cylindrical lenticular array 2, the section is perpendicular to an axis A of extension of the cylinders. Under the lenticular network 2 is disposed at least one image layer 4, 5. This image layer 4, 5 is periodically divided into sections 10, each section 10 corresponding to a lenticule 3 and is substantially opposite a lenticule 3. Each Section 10 comprises segments 6-9 of patterns A, B. Figure 1 illustrates an example with two patterns A, B, but it is possible to have more patterns.

Due to the shape of the lenticule 3, an observer sees the segments 6 or 8 of a first pattern A when looking along a first axis of vision Da. From all the segments 6 or 8 of all the sections 10 of a device 1, the eye reconstructs the first pattern A. Similarly, an observer sees the segments 7 or 9 of a second pattern B when he is looking at along a second axis of vision t3. From all segments 7 or 9 of all sections 10 of a device 1, the eye reconstructs the second pattern B.

So that a segment 6, 8 of the first pattern A and a segment 7, 9 of the second pattern B do not overlap, at the risk of disturbing the rendering of one of the patterns A, B, it is necessary to respect a multiple angle py an "angular step" y between the orientation a of the first axis of vision Aa and the orientation p of the second axis of vision OR. If the first axis of vision Aa, respectively the second axis of vision i3, has, with respect to a reference, such as the normal AN on the surface of the device 1, an angle α, respectively an angle p, the angle α between the first axis of vision Da and the second axis of vision i3, is multiple of the "angular step" y, according to a relation py = Ra, with p integer. It is clear that to respect such an "angular pitch" is to respect a precise spacing between the segments 6, 8 of a first pattern A on the one hand and the segments 7, 9 of a second pattern B on the other go. As seen previously, there are at least two known embodiments of multiple patterns A, B, with a lenticular array 2. A first embodiment "pre-printed" consists in arranging a specially adapted image layer 5 in a Such an image layer 5 is decomposed into segments 8 corresponding to a first pattern A and into segments 9 corresponding to a second pattern B. The content of the segments 8, 9 depends on the respective content of the different patterns A, B. The location of the segments 8, 9 depends on the characteristics of the lenticular network 2. Thus the segments 8, 9 must be located in the sections 10. The periodicity of the segments 8, 9 must respect the periodicity of the lenticules 3 of the lenticular network 2. In this case, "pre-printed" embodiment, the respect of the "angular pitch" y characteristic of the lenticular network 2 is obtained by a correct spacing of the segments 8 of a first pattern A r to the segments 9 of a second pattern B. In this embodiment, an image comprising the different patterns is typically made by printing, for example offset. Such an embodiment thus advantageously makes it possible to produce one or more patterns A, B in color. The accuracy of this printing intrinsically makes it possible to respect a periodicity and a relative positioning of the segments 8, 9 of different patterns A, B which guarantees the respect of an "angular step" y. The printing of this image can be performed on an image layer 5, then assembled with / under the lenticular network 2. Alternatively, the printing of this image can be directly performed on the back plane of the lenticular network 2, which Then, it should be noted that in both cases it is impossible to obtain a repeatable positioning of the image relative to the lenticular array 2. A lenticular array 2 typically has a period / width of section 10 between 30 pm and 1 mm, preferably between 60 and 150 pm. This results from inaccuracies in the positioning of the image layer 5 with respect to the lenticular array 2, during the step of assembling a printed image layer 5 under a lenticular array 2, or inaccuracies in the printing of the image relative to the lenticular network 2. lenticular network 2, during the direct printing step 35 under the lenticular network 2, an unavoidable relative positioning uncertainty between the image and the lenticular network 2.

It results from this uncertainty that the angle OE of a first axis of vision Aa of a first printed pattern A is undetermined and can not be known in advance. The angle is the result of the manufacturing process and can only be known after assembly / printing of the image layer 5 and the lenticular network 2. It is the same for the angle p of a second axis of vision Ap d a second pattern B printed. Despite this, compliance with the "angular pitch" relative thereto between a first axis of vision Ac (and a second axis of vision np, because of the intrinsic precision of the printing process, is achieved, and guarantees the effect of patterns multiple A, B, each visible under an axis of vision La, Ap separate partner.

A second "post-etched" embodiment uses an editable layer 4. Such an editable layer 4 is assembled under a lenticular array 2. It is then etched, typically by means of a beam, such as a laser beam, through said lenticular array 2. This etching is thus advantageously carried out remotely and a posteriori, after assembly of the lenticular network 2 and the different layers 4, 5. This etching, by varying the position and intensity of the beam, comes by energy input, modifying said modifiable layer 4 and perform by etching at minus a pattern A, B by etching the corresponding segments 6 and / or 7. A lenticule 3 is optically used here in an optical path opposite to that of vision. However, such a path is symmetrical and by directing the beam, relative to the device 1, along a main axis during the etching of a pattern A, respectively B, this main axis of etching determines an axis of vision fia, respectively i3, according to which said pattern A, respectively B, thus etched is then visible. Thus a pattern A, respectively a pattern B, visible from an axis of vision Da, respectively np, must be etched by orienting the etching beam along said axis of vision Da, respectively Ap. Referring to FIG. 1, beam oriented according to the first axis Acx, engraves in layer 4 modifiable, a segment 6 of a first pattern A. first pattern A will then be visible according to this first Aa. Similarly, a beam oriented along second axis Ap, engraves in a modifiable layer 4, segment 7 of a second pattern B. This second pattern B will then be visible along this second axis OR. It is thus possible, by modifying the orientation of the device 1 or the engraving beam by a multiple angle py of the "angular pitch" between two engravings, to respect the "angular pitch" y and to make patterns A, B multiple and distinct separately visible each according to a line of sight, without interference between the patterns. It should be noted that because of the modification principle, etching only makes it possible to produce monochrome patterns. Typically, the etching beam burns a layer 4, for example of transparent polycarbonate, enriched in carbon. This burn reveals carbon black. Advantageously a substrate or a white bottom layer provides a contrasting screen. Modulation of the beam power makes it possible to achieve a wide variety of gray levels. The respect of the "angular step" relating thereto is here obtained by an orientation change of an angle py multiple of the "angular step" y, between a first angle of etching a of a first pattern A, known because arbitrarily chosen to engrave a first pattern A and a second engraving angle p, a second pattern B. A combination of the two previous embodiments by printing (pre-printed) and etching (post-engraved) simply seems impossible. Indeed, such a combination faces the following problem. Assuming that at least one first pattern A is produced by printing, the orientation a of its axis of vision Da is not a known one, because of the uncertainty introduced by the assembly of the image layer 5 with the lenticular network 2. To then consider an engraving of a second pattern B it is imperative to know the said orientation in order to respect the "angular step" y. The orientation of the engraving beam can only be done relative to an angle α of an axis of vision Acc of a pattern A previously made. This difficulty is exploited in that it makes complex a series manufacture of a safety device 1. Circumvention of this difficulty implies according to the invention a step of individual recovery and precision metrology of each device 1 This makes it very difficult to reproduce the manufacturing process and therefore the device 1. According to the invention, a safety device is manufactured according to a method illustrated in FIG. 2 and comprising the following steps. A first step is to print El at least one first pattern A on an image layer 5, so that it is visible through a lenticular array 2. Thus, said at least one first pattern A is made according to FIG. first embodiment "pre-printed" previously described by prior printing followed by an assembly 25 under the lenticular array 2. The fact that said at least one pattern A is visible through a lenticular array 2 implies that its printing is segmented into segments 8, 9 respecting an "angular step" y of said lenticular array 2. This "angular step" y, at the level of the print El, results in the respect of a spatial period in the image as well printed. Thus for a cylindrical lenticular network 2, the image layer 5 is printed respecting parallel strips of width equal to the period 10 of the lenticular network 2. Each such band is divided into n sub-parallel disjoint strips, where n is the total number , printed and / or engraved with desired motifs in the end. These patterns are divided into patterns printed in an image layer 5 in step E1 and in patterns etched in an editable layer 4 in a step E6 described above. Likewise for a generalized lenticular network 2, the image layer 5 is printed respecting a checkerboard / matrix corresponding to the checker / layout matrix of the lenticules 3. After printing El, said at least one first pattern A is assembled E2 under said network The two preceding 10 printing steps E1 and E2 assembly are distinct when the printing E1 is performed on an image layer 5, then assembled under the lenticular network 2. The two previous steps of printing E1 and E2 On the contrary, the assembly E2 is identical when the impression E1 is directly made on the back, on the smooth face, of the lenticular array 2. In both cases, the assembly step E2 introduces an uncertainty as to the orientation of the axis (or axes if the printed patterns A are multiple) Acx vision under which is visible the pattern A. This uncertainty is such that safety devices 1 disposed on a plate of fabricat ion, for which the assembly E2 is also made with a single image layer 5 covering the entire plate, do not produce identical axes of vision Acx from a device 1 to the other belonging to the same plate. In order to overcome this uncertainty, and to be able to carry out the step E6 of etching another pattern B, it is advisable to determine E3 precisely the axis of vision da of at least one pattern A. It should be noted here that if several patterns A have been printed, they necessarily respect between each other the "angular pitch" y of the lenticular array 2. The determination step E3 can therefore be carried out only for one of these patterns A, the axis of vision Aa possible other printed patterns deduced by applying a rotation of angle py multiple "angular step", depending on the characteristics of the lenticular network 2. Also the determination step E3 is it here described only for a first pattern A. The determination of the axis of vision Aa of the first pattern A is performed by a metrological system capable of varying the relative orientation between a security device 1 and an optical detector. The optical detector is able to determine that it is aligned with the optical axis Aa when it perceives a pattern A with a clear vision. When this clear vision is obtained, the system raises the exact relative orientation of the device 1. The optical detector may be a human eye. However, in order to automate the process, the optical detector is advantageously an image sensor such as a camera, advantageously coupled with an image analysis software capable of detecting when a pattern A is visible and sharp. The orientation of an axis of vision Ac (thus obtained is recorded in the form of angles, these angles, typically two in a general case, can be expressed in any reference point.) Advantageously, by simplifying the reference, it is possible to This simplification is possible by considering only the angle made by the axis of vision Aa with the normal AN to the device 25 It is still possible to simplify the reference when the lenticular network 2 is cylindrical, in which case the problem is unidimensional, the safety device 1 is oriented only along an axis parallel to the axis A of the cylinders, around this axis A, or what is equivalent in a perpendicular plane. at the said axis A, the axis of vision Aa does with the normal AN to the device an angle A. Once the orientation of the axis of vision Aa of the first pattern A is identified, the method has an absolute reference. is then possible according to the 'no 35 angula ire y, known as a characteristic of the lenticular network 2, and characteristics of said angular network 2, to orient the safety device 1 according to a second axis of vision OR. This is done during a step E4 which applies to the safety device 1 a rotation of an angle respecting the "angular step" y. In the case of a cylindrical network, said rotation 5 is applied around the axis L of the cylinders and at an angle p.y multiple of the "angular step" y, with p integer. The device 1 is then oriented along a second axis of vision Ap. It is then possible to proceed to the next step of making E6 of at least a second pattern B along said second axis of vision OR through the lenticular network. 2. Such an embodiment E6 through the lenticular network 2 involves using the second embodiment, the "post-etched" mode. It is possible to repeat the steps E4 and E6, and to engrave a pattern B along an axis of vision Ap, and then to apply a new rotation at another angle py multiple of the "angular step" y in order to engrave again another reason. The determination step E3 of the orientation of a first axis of vision Aa can only be done after the assembly step E2 of the said at least one first pattern A, since it is during assembly. E2 is randomly configured the orientation OE of the axis of vision Da. The determination step E3 of the orientation of the vision axis Aa must be done before any realization step E6, so that the realization E6 carries out said at least one second engraved pattern B correctly arranged relative to said at least one first pattern A printed and correctly arranged relative to any possible second pattern B engraved 30 already made. This step E3 is important in that in its absence, an embodiment E6, for example in an arbitrary orientation, is likely to produce a second engraved pattern interfering with one of said first printed patterns. The security device 1 resulting from such a method is difficult to reproduce, in that a second etched pattern depends, for its realization E6 is possible, the orientation of the axis of vision 8. (ix d In order to reinforce the security of the safety device 1 obtained, by mixing even more intimately said first printed patterns and said second etched patterns and the two steps E1 / E2 and E6 respectively producing them, it is advantageous to add, prior to the realization step E6, a construction step E5 of said at least one second pattern This construction step E5 creates a second pattern, possibly by modifying a second pre-existing pattern. include said angle α of the first axis of vision, a, characteristic of a first printed pattern, not only in the step of producing the second etched pattern, but also in the content of the second pattern itself. , according to one embodiment, the second etched pattern comprises a representation of the angle α or alternatively or complementarily to the orientation angle f3 of the axis of vision if3 of the second etched pattern. This is equivalent. Indeed, as seen above the angle a and the angle f3 are necessarily linked by a relationship with the "angular step" y. Such a representation may be a numerical value of the angle a or p or else a graphic representation of the said angle α or f3 or any other coded representation of the angle α or R. Such an arrangement advantageously makes it possible to verify the authenticity of the safety device 1 by checking that the coding of the angle cx, respectively p, contained and therefore visible in the second etched pattern corresponds to the angle a, respectively f3, of the effective orientation of the axis of vision AOE, respectively OR, under which can be seen a first printed pattern, respectively a second engraved pattern, on the security device 1 considered. The building step E5 of the second etched pattern may also be such that the content of said second etched pattern is a function of a position YA of a first printed pattern A relative to the device 1. In effect, as in the case of angle a, this position YA varies randomly, from one device to the other, essentially for the same reasons of reproducibility of the relative positioning of a first pattern A printed relative to the lenticular network 2 during the printing steps E1 and d E2 assembly. Similarly, the position YA of a first printed pattern A can be introduced into the contents of a second engraved pattern B. According to another embodiment, the position YA of the printed pattern A can be used to position relatively all or part of a second engraved pattern B. In order to be able to make at least one second engraved pattern B through the lenticular network 2, the assembly step E2 further comprises an addition, in addition to the image layer 5, of a layer 4 of modifiable material. This modifiable layer 4 is assembled with the image layer 5 under the lenticular array 2. It can be indifferently arranged under a transparent image layer 5, or alternatively inserted between an image layer 5 and the lenticular network 2, as illustrated in FIG. In this second case, the modifiable layer 4 is advantageously transparent. The transparency of the upper layer, among the image layer 5 or the modifiable layer 4, means at least portions covering the useful segments of the layer below. Thus, in the configuration of FIG. 1, the image layer 5 is printed on a segment 8 of a first pattern A. The modifiable layer 4, situated above, is advantageously transparent, at least to the right of said segment 8, or at least level of the segment 6 of the modifiable layer 4. Said transparency "to the right of" means along an optical path, or along an axis of vision, 8, a, a.

It can be noted that in Figure 1 some segments, corresponding to the same pattern are superimposed. Thus a segment 8 corresponds to a pattern A printed. A segment 6 would correspond to a pattern A if the latter was engraved. If the pattern A is printed, the segment 6 is left free / transparent, so that a printed segment 8 can be seen. If the pattern B is etched, the segment 7 is used. A segment 9 corresponds to a pattern B printed. If pattern B is etched, segment 9 is unused. It is also possible to spatially combine the two embodiments "pre-printed" and "post-engraved" to achieve the same pattern A or B with a first part of the surface of the printed pattern and a second part of the surface of the engraved pattern. It goes without saying that the first part and the second part are necessarily disjointed. Thus, with reference to FIG. 1, if a pattern A is partially printed, the pixels / strips in a first printed area portion use the segment 8. On the contrary the pixels / strips in a second etched area portion use the segment 6 In this variegated embodiment, the direction p of the axis of vision of a second etched portion coincides with the direction a of the axis of vision na of a first printed portion. The "angular step" is again respected here, with a value p-cx = p.y = 0, ie p = 0. Such a variegated embodiment again requires knowing the angle a under which is visible the first printed part of the pattern. This is necessary to arrange the etching tool at an angle p identical to said angle aafin to engrave the second part. Since the modifiable layer 4 has been assembled with the lenticular network 2 in step E2, the step of producing E6 of at least one second etched pattern can be carried out by etching in the material of the modifiable layer 4, by means of FIG. a directional thermal beam, such as a laser beam. This beam carries out an etching, through the lenticular network 2, along the axis of vision, 843 associated with said second pattern B. Said at least one first pattern is printed on a surface finally disposed under the smooth underside of the lenticular array 2. This can be done, according to one embodiment, by printing on a separate image layer 5 during printing, and then assembled under the lenticular array 2. According to another embodiment this can be obtained by direct printing on the The invention also relates to a safety device 1. This safety device 1 comprises at least a first pattern A visible through a lenticular array 2 according to a first axis of vision AOE associated and the at least one second pattern B visible through said lenticular array 2 according to a second associated viewing axis AP, each second viewing axis OR being oriented relatively at least a first axis of vision Acc respecting a "angular step" y characteristic of the lenticular network 2. Such a safety device 1 could be made only according to a first embodiment "pre-printed" where all the patterns are printed on an image layer 5. Similarly, such a safety device 1 could be made only according to a second "post-engraved" embodiment where all the patterns are etched in an editable layer 4 through the lenticular network 2. However, according to an important additional feature of the invention, said at least one second pattern B is a function of at least an angle α of a first axis of vision Acc, identified for example relative to a normal AN device 1. It is important to note that such a safety device 1, where a first pattern is produced by printing El / assembly E2 according to the first embodiment "pre-printed" and one of uxth pattern is achieved by etching E6 through the lenticular array 2 according to the second embodiment "post-engraved" is not comparable neither with a device where all the patterns are printed, nor with a device where all the patterns are etched . A detailed analysis of a device 1 makes it possible to determine, on the final product, the embodiment of each pattern. A simple way is the analysis of the image layer 5 and / or the modifiable layer 4, most often distinct. An etched pattern has detectable deformations / burns of an editable layer 4, while a printed pattern exhibits only ink deposits on an image layer 5. The fact that said at least one second etched pattern is a function of an angle α of at least a first axis of vision Aa necessarily implies that this angle a is known at the time of producing a second etched pattern. For this the only solution is to use a second embodiment engraved for a second etched pattern. As previously indicated, said angle a may be contained in the second etched pattern, for example by its value. It can still be by a transformation of the second engraved pattern according to the angle OE or what is equivalent function of the angle p. According to another characteristic, a second etched pattern 20 may still be a function of the position YA of at least one first printed pattern. This position YA is tainted with uncertainty and therefore randomly individualized, because of the assembly step. Also, it must necessarily be measured, by a metrology step performed individually for each device 1, similar to that for determining the angle cx, with similar means. An advantageous way of producing a second etched pattern according to the angle α of the axis of vision Da of a first printed pattern is to apply a transformation T to the second etched pattern before it is etched, said transformation T being a function of the angle OE or the angle r3. Such a transformation T, particularly advantageous in that it allows a simple visual control, is such that it corrects on the second etched pattern the effect produced by a rotation Rp orienting the second axis of vision i3 according to the normal AN, so that said at least one second etched pattern does not appear deformed when viewed according to the second axis of vision Ap. Thus, as shown in FIG. 3, a pattern B, if etched without prior transformation, when 'It is seen under the axis of vision Ap, is deformed. Indeed, the fact of orienting the safety device 1 along the axis of vision Ap so that the pattern B is visible, requires a rotation Rp, the device 1 of an angle p relative to the normal AN. Such a rotation Rp causes a deformation of the pattern B which is not seen according to the normal AN to the device 1. The transformation T advantageously corrects this effect by an inverse deformation. Thus in the case where the safety device 1 is plane, a rotation Rp causes an optical deformation of the pattern B in a direction perpendicular to the axis A of the rotation Rp. Also, the application of a transformation T, compressing the dimension Y multiplied by a coefficient K = 20 sin p applied before etching to the pattern B corrects said deformation. Thus, the pattern B, as seen from the axis of vision 0 [3, appears undeformed, with a normal 1: 1 ratio. The application of such a transformation T requires a precise knowledge of the angle p and therefore previously the angle at which it is linked by the "angular step" y. The final effect is simple to verify in order to prove the authenticity of the safety device 1 thus produced. The pattern B must appear unmodified, when viewed along the axis of vision Ap. For an angle p of 70 °, the dimension Y is multiplied by K = 0.94. For an angle p of 90 °, the dimension Y is unchanged, K = 1. It has been seen that a second etched pattern can also be made taking into account the actual position YA of a first printed pattern. A particularly interesting embodiment of this feature consists in producing a safety device 1 in which a second etched pattern, as seen along a second associated axis of vision Ap, is complementary to a first printed pattern, as seen according to a first axis of vision Acx associated.

Such complementarity appears, and can thus simply be verified, by orienting the safety device 1 successively along the axis of vision Aa and along the axis of vision AR. Thus, a rotation Ry, at a multiple angle py of the "angular step" y, orienting the second axis of vision Ap along the first axis of vision, 8, a, superimposes the first printed pattern and the second etched pattern and makes appear their complementarity. The complementarity of a first printed pattern and a second engraved pattern can take many forms. The complementarity can be geometric. Thus a second etched pattern, respectively a first printed pattern, can be fitted edge to edge with a first printed pattern, respectively a second engraved pattern. As illustrated in FIG. 4, a second engraved pattern B 20 visible along an axis of vision L3, respectively a first pattern A printed visible along an axis of vision Aa, can come to frame a first pattern A printed, respectively a second pattern. B engraved, by a complementary shape, thus creating a juxtaposition effect at a flip-flop from the axis of vision Acx towards the axis of vision Ap and vice versa. The complementarity can be formed by two complementary motifs, for example, to create an apparent movement effect. This is illustrated in FIG. 5 where the printed pattern A and the engraved pattern B include, for example, nested arrows, which on the flip-flop give an impression of rightward movement. Complementarity can still be colored. Thus, as illustrated in FIG. 6, a printed pattern A comprises a picture in a first frame and an engraved pattern B comprises a second frame of another color but covering the first frame identically.

A second engraved pattern B is (necessarily) made in gray, while a first printed pattern A can be made using a different color. Because of the embodiment, a first pattern A printed may be polychrome, while a second pattern B engraved is necessarily monochrome. Such a combination is advantageous in terms of feasibility and attractiveness for the user. In all of these nonlimiting examples of complementarity, a precise geometric "fit" is made between a first printed pattern A and a second engraved pattern B. Such an adjustment requires a very precise knowledge of both the angle α and the position YA of the first printed pattern A, in order to place the second pattern B, by etching, accordingly. The final effect thus obtained is advantageously difficult to obtain, since it requires at least one delicate metrology step, and at the same time easy to control visually, including without the need for tools. The principle of the invention can be varied to many different embodiments. It is possible to make one or more printed patterns on all or part of the surface of the device 1, each visible along an associated axis of vision. By measuring the angle of such an associated axis of vision, it is then possible to produce one or more engraved patterns respecting the "angular pitch" of the lenticular array 2 between them and with the printed patterns. An engraved pattern may even be engraved along an axis of vision associated with a printed pattern, provided that the surface of the device 1 is divided between a first portion used by the printed pattern and a part used by the engraved pattern, the first and the second part being used. second parts being disjoint. In the case where the lenticular network 2 is cylindrical, it has an axis of extension A coincides with the axis A of the cylinders. In this case the "angular step" y, characteristic of the lenticular network 2 is measured around said axis A. The axis A is still coincident with the axis of the rotations Ra, Rp, Ry.

The safety device 1 described above may be disposed on any support, of any shape, by any known assembly means. The invention also relates to the application of a security device according to one of the embodiments 10 described, to produce an identity document, such as an identity card, a passport, a registration certificate, a credit card , etc., thus rendered unfalsifiable.

Claims (13)

REVENDICATIONS1. Security device comprising at least a first pattern (A) visible through a lenticular array (2) according to a first axis of vision (Ac) associated and at least one second pattern (B) visible through said lenticular array (2) ) according to a second axis of vision (4) associated, each second axis of vision (4) being oriented relative to at least a first axis of vision (Acx) according to a "pitch angle" (y) characteristic of the lenticular network (2 ) characterized in that said at least one second pattern (B) is a function of at least one angle (a) of a first axis of vision (AOE) relative to a normal (AN) to the device (1). 2. Device according to claim 1, wherein the second pattern (B) is a function of at least one position (YA) of a first pattern (A) relative to the device (1). 20 3. Device according to claim 1 or 2, wherein the second pattern (B) is deformed by applying a transformation (T) function of at least one angle (a) of at least a first axis of vision (AOE). . 25 4. Device according to claim 3, wherein said transformation (T) is such that it corrects on said at least one second pattern (B) the effect produced by a rotation (R3) orienting the second axis of vision (4) 30 according to the normal (AN), so that said at least one second pattern (B) does not appear deformed when viewed according to the second axis of vision (4). 5. Device according to claim 4, wherein the device 35 (1) is plane and wherein said transformation (T) is an application of a multiplier coefficient (K) to the dimension (Y) of the second pattern (B) perpendicular to a axis (A) a rotation (R (3) orienting the second axis of vision (A (3) according to the normal (AN), said ratio (K) being equal to the sine of the angle ((3) of the second axis of vision (A3) relative to the normal (AN). 6. Device according to any one of claims 2 to 5, wherein a second pattern (B), as seen along a second axis of vision (A (3) associated, is complementary to a first pattern (A), such that seen according to a first axis of vision (Da) 10 associated. 7. Device according to any one of claims 1 to 6, wherein the lenticular array (2) is cylindrical along an axis of extension (A). 15 8. Identity document comprising a device (1) for security according to any one of the preceding claims. 20 9. A method of manufacturing a device (1) security characterized in that it comprises the following steps - printing (El) of at least a first pattern (A) adapted to be seen through a lenticular network (2), - assembling (E2) said pattern (A) printed under said lenticular network (2), - determining (E3) a first axis of vision (Da) according to which a first pattern (A) is visible, rotation (E4) of the device (1) according to an "angular pitch" (y) characteristic of the lenticular array (2) in order to present the device (1) along a second axis of vision (8, [3), - embodiment (E6) a second pattern (B) according to the second axis of vision (4) through the lenticular network (2). 35 10. The method of claim 9, further comprising, prior to the embodiment step (E6), a deconstruction step (E5) of the second pattern (B) so that its content is a function of an angle (a) of the first axis of vision (AOE) relative to a normal (AN) device (1). 11. The method of claim 9 or 10, further comprising, prior to the embodiment step (E6), a construction step (E5) of the second pattern (B) so that its content is a function of the position (YA) of a first pattern (A) relative to the device (1). 12. The method of claim 10 or 11, wherein the step of construction (E5) is such that the second pattern (B) has a complementarity with the first pattern (A). 15 The method according to any of claims 9 to 12, wherein the assembling step (E2) comprises adding a layer of modifiable material (5), and wherein the step of producing (E6) the second pattern (B) comprises etching in said layer of modifiable material (5) by means of a beam, through the lenticular network (2).